def pointcloud_color_from_image(
        nusc: NuScenes, pointsensor_token: str,
        camera_token: str) -> Tuple[np.array, np.array]:
    """
    Given a point sensor (lidar/radar) token and camera sample_data token, load pointcloud and map it to the image
    plane, then retrieve the colors of the closest image pixels.
    :param nusc: NuScenes instance.
    :param pointsensor_token: Lidar/radar sample_data token.
    :param camera_token: Camera sample data token.
    :return (coloring <np.float: 3, n>, mask <np.bool: m>). Returns the colors for n points that reproject into the
        image out of m total points. The mask indicates which points are selected.
    """

    cam = nusc.get('sample_data', camera_token)
    pointsensor = nusc.get('sample_data', pointsensor_token)

    pc = LidarPointCloud.from_file(
        osp.join(nusc.dataroot, pointsensor['filename']))
    im = Image.open(osp.join(nusc.dataroot, cam['filename']))

    # Points live in the point sensor frame. So they need to be transformed via global to the image plane.
    # First step: transform the pointcloud to the ego vehicle frame for the timestamp of the sweep.
    cs_record = nusc.get('calibrated_sensor',
                         pointsensor['calibrated_sensor_token'])
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix)
    pc.translate(np.array(cs_record['translation']))

    # Second step: transform to the global frame.
    poserecord = nusc.get('ego_pose', pointsensor['ego_pose_token'])
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix)
    pc.translate(np.array(poserecord['translation']))

    # Third step: transform into the ego vehicle frame for the timestamp of the image.
    poserecord = nusc.get('ego_pose', cam['ego_pose_token'])
    pc.translate(-np.array(poserecord['translation']))
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix.T)

    # Fourth step: transform into the camera.
    cs_record = nusc.get('calibrated_sensor', cam['calibrated_sensor_token'])
    pc.translate(-np.array(cs_record['translation']))
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix.T)

    # Fifth step: actually take a "picture" of the point cloud.
    # Grab the depths (camera frame z axis points away from the camera).
    depths = pc.points[2, :]

    # Take the actual picture (matrix multiplication with camera-matrix + renormalization).
    points = view_points(pc.points[:3, :],
                         np.array(cs_record['camera_intrinsic']),
                         normalize=True)

    # Remove points that are either outside or behind the camera. Leave a margin of 1 pixel for aesthetic reasons.
    mask = np.ones(depths.shape[0], dtype=bool)
    mask = np.logical_and(mask, depths > 0)
    mask = np.logical_and(mask, points[0, :] > 1)
    mask = np.logical_and(mask, points[0, :] < im.size[0] - 1)
    mask = np.logical_and(mask, points[1, :] > 1)
    mask = np.logical_and(mask, points[1, :] < im.size[1] - 1)
    points = points[:, mask]

    # Pick the colors of the points
    im_data = np.array(im)
    coloring = np.zeros(points.shape)
    for i, p in enumerate(points.transpose()):
        point = p[:2].round().astype(np.int32)
        coloring[:, i] = im_data[point[1], point[0], :]

    return coloring, mask
    def map_pointcloud_to_image(self,
                                pointsensor_token: str,
                                camera_token: str,
                                min_dist: float = 1.0) -> Tuple:
        """
        Given a point sensor (lidar/radar) token and camera sample_data token, load point-cloud and map it to the image
        plane. [Recoded from the NuscenesExplorer class so the image is not to be loaded].
        :param pointsensor_token: Lidar/radar sample_data token.
        :param camera_token: Camera sample_data token.
        :param min_dist: Distance from the camera below which points are discarded.
        :return (pointcloud <np.float: 2, n)>, coloring <np.float: n>).
        """

        cam = self.nusc.get('sample_data', camera_token)
        pointsensor = self.nusc.get('sample_data', pointsensor_token)
        pcl_path = os.path.join(self.nusc.dataroot, pointsensor['filename'])
        if pointsensor['sensor_modality'] == 'lidar':
            pc = LidarPointCloud.from_file(pcl_path)
        else:
            pc = RadarPointCloud.from_file(pcl_path)

        # Points live in the point sensor frame. So they need to be transformed via global to the image plane.
        # First step: transform the point-cloud to the ego vehicle frame for the timestamp of the sweep.
        cs_record = self.nusc.get('calibrated_sensor', pointsensor['calibrated_sensor_token'])
        pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix)
        pc.translate(np.array(cs_record['translation']))

        # Second step: transform to the global frame.
        poserecord = self.nusc.get('ego_pose', pointsensor['ego_pose_token'])
        pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix)
        pc.translate(np.array(poserecord['translation']))

        # Third step: transform into the ego vehicle frame for the timestamp of the image.
        poserecord = self.nusc.get('ego_pose', cam['ego_pose_token'])
        pc.translate(-np.array(poserecord['translation']))
        pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix.T)

        # Fourth step: transform into the camera.
        cs_record = self.nusc.get('calibrated_sensor', cam['calibrated_sensor_token'])
        pc.translate(-np.array(cs_record['translation']))
        pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix.T)

        # Fifth step: actually take a "picture" of the point cloud.
        # Grab the depths (camera frame z axis points away from the camera).
        depths = pc.points[2, :]

        # Retrieve the color from the depth.
        coloring = depths

        # Take the actual picture (matrix multiplication with camera-matrix + renormalization).
        points = view_points(pc.points[:3, :], np.array(cs_record['camera_intrinsic']), normalize=True)

        # Remove points that are either outside or behind the camera. Leave a margin of 1 pixel for aesthetic reasons.
        # Also make sure points are at least 1m in front of the camera to avoid seeing the lidar points on the camera
        # casing for non-keyframes which are slightly out of sync.
        mask = np.ones(depths.shape[0], dtype=bool)
        mask = np.logical_and(mask, depths > min_dist)
        mask = np.logical_and(mask, points[0, :] > 1)
        mask = np.logical_and(mask, points[0, :] < 1600 - 1)    # hardcoded width
        mask = np.logical_and(mask, points[1, :] > 1)
        mask = np.logical_and(mask, points[1, :] < 900 - 1)   # hardcoded height
        points = points[:, mask]
        coloring = coloring[mask]

        return points, coloring
def export_scene_pointcloud(nusc: NuScenes,
                            out_path: str,
                            scene_token: str,
                            channel: str = 'LIDAR_TOP',
                            min_dist: float = 3.0,
                            max_dist: float = 30.0,
                            verbose: bool = True) -> None:
    """
    Export fused point clouds of a scene to a Wavefront OBJ file.
    This point-cloud can be viewed in your favorite 3D rendering tool, e.g. Meshlab or Maya.
    :param nusc: NuScenes instance.
    :param out_path: Output path to write the point-cloud to.
    :param scene_token: Unique identifier of scene to render.
    :param channel: Channel to render.
    :param min_dist: Minimum distance to ego vehicle below which points are dropped.
    :param max_dist: Maximum distance to ego vehicle above which points are dropped.
    :param verbose: Whether to print messages to stdout.
    """

    # Check inputs.
    valid_channels = [
        'LIDAR_TOP', 'RADAR_FRONT', 'RADAR_FRONT_RIGHT', 'RADAR_FRONT_LEFT',
        'RADAR_BACK_LEFT', 'RADAR_BACK_RIGHT'
    ]
    camera_channels = [
        'CAM_FRONT_LEFT', 'CAM_FRONT', 'CAM_FRONT_RIGHT', 'CAM_BACK_LEFT',
        'CAM_BACK', 'CAM_BACK_RIGHT'
    ]
    assert channel in valid_channels, 'Input channel {} not valid.'.format(
        channel)

    # Get records from DB.
    scene_rec = nusc.get('scene', scene_token)
    start_sample_rec = nusc.get('sample', scene_rec['first_sample_token'])
    sd_rec = nusc.get('sample_data', start_sample_rec['data'][channel])

    # Make list of frames
    cur_sd_rec = sd_rec
    sd_tokens = []
    while cur_sd_rec['next'] != '':
        cur_sd_rec = nusc.get('sample_data', cur_sd_rec['next'])
        sd_tokens.append(cur_sd_rec['token'])

    # Write point-cloud.
    with open(out_path, 'w') as f:
        f.write("OBJ File:\n")

        for sd_token in tqdm(sd_tokens):
            if verbose:
                print('Processing {}'.format(sd_rec['filename']))
            sc_rec = nusc.get('sample_data', sd_token)
            sample_rec = nusc.get('sample', sc_rec['sample_token'])
            lidar_token = sd_rec['token']
            lidar_rec = nusc.get('sample_data', lidar_token)
            pc = LidarPointCloud.from_file(
                osp.join(nusc.dataroot, lidar_rec['filename']))

            # Get point cloud colors.
            coloring = np.ones((3, pc.points.shape[1])) * -1
            for channel in camera_channels:
                camera_token = sample_rec['data'][channel]
                cam_coloring, cam_mask = pointcloud_color_from_image(
                    nusc, lidar_token, camera_token)
                coloring[:, cam_mask] = cam_coloring

            # Points live in their own reference frame. So they need to be transformed via global to the image plane.
            # First step: transform the point cloud to the ego vehicle frame for the timestamp of the sweep.
            cs_record = nusc.get('calibrated_sensor',
                                 lidar_rec['calibrated_sensor_token'])
            pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix)
            pc.translate(np.array(cs_record['translation']))

            # Optional Filter by distance to remove the ego vehicle.
            dists_origin = np.sqrt(np.sum(pc.points[:3, :]**2, axis=0))
            keep = np.logical_and(min_dist <= dists_origin,
                                  dists_origin <= max_dist)
            pc.points = pc.points[:, keep]
            coloring = coloring[:, keep]
            if verbose:
                print('Distance filter: Keeping %d of %d points...' %
                      (keep.sum(), len(keep)))

            # Second step: transform to the global frame.
            poserecord = nusc.get('ego_pose', lidar_rec['ego_pose_token'])
            pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix)
            pc.translate(np.array(poserecord['translation']))

            # Write points to file
            for (v, c) in zip(pc.points.transpose(), coloring.transpose()):
                if (c == -1).any():
                    # Ignore points without a color.
                    pass
                else:
                    f.write(
                        "v {v[0]:.8f} {v[1]:.8f} {v[2]:.8f} {c[0]:.4f} {c[1]:.4f} {c[2]:.4f}\n"
                        .format(v=v, c=c / 255.0))

            if not sd_rec['next'] == "":
                sd_rec = nusc.get('sample_data', sd_rec['next'])
Beispiel #4
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    def nuscenes_gt_to_kitti(self) -> None:
        """
        Converts nuScenes GT annotations to KITTI format.
        """
        kitti_to_nu_lidar = Quaternion(axis=(0, 0, 1), angle=np.pi / 2)
        kitti_to_nu_lidar_inv = kitti_to_nu_lidar.inverse
        imsize = (1600, 900)

        token_idx = 0  # Start tokens from 0.

        # Get assignment of scenes to splits.
        split_logs = create_splits_logs(self.split, self.nusc)

        # Create output folders.
        label_folder = os.path.join(self.nusc_kitti_dir, self.split, 'label_2')
        calib_folder = os.path.join(self.nusc_kitti_dir, self.split, 'calib')
        image_folder = os.path.join(self.nusc_kitti_dir, self.split, 'image_2')
        lidar_folder = os.path.join(self.nusc_kitti_dir, self.split,
                                    'velodyne')
        for folder in [label_folder, calib_folder, image_folder, lidar_folder]:
            if not os.path.isdir(folder):
                os.makedirs(folder)

        # Use only the samples from the current split.
        sample_tokens = self._split_to_samples(split_logs)
        sample_tokens = sample_tokens[:self.image_count]

        tokens = []
        for sample_token in sample_tokens:

            # Get sample data.
            sample = self.nusc.get('sample', sample_token)
            sample_annotation_tokens = sample['anns']
            cam_front_token = sample['data'][self.cam_name]
            lidar_token = sample['data'][self.lidar_name]

            # Retrieve sensor records.
            sd_record_cam = self.nusc.get('sample_data', cam_front_token)
            sd_record_lid = self.nusc.get('sample_data', lidar_token)
            cs_record_cam = self.nusc.get(
                'calibrated_sensor', sd_record_cam['calibrated_sensor_token'])
            cs_record_lid = self.nusc.get(
                'calibrated_sensor', sd_record_lid['calibrated_sensor_token'])

            # Combine transformations and convert to KITTI format.
            # Note: cam uses same conventions in KITTI and nuScenes.
            lid_to_ego = transform_matrix(cs_record_lid['translation'],
                                          Quaternion(
                                              cs_record_lid['rotation']),
                                          inverse=False)
            ego_to_cam = transform_matrix(cs_record_cam['translation'],
                                          Quaternion(
                                              cs_record_cam['rotation']),
                                          inverse=True)
            velo_to_cam = np.dot(ego_to_cam, lid_to_ego)

            # Convert from KITTI to nuScenes LIDAR coordinates, where we apply velo_to_cam.
            velo_to_cam_kitti = np.dot(velo_to_cam,
                                       kitti_to_nu_lidar.transformation_matrix)

            # Currently not used.
            imu_to_velo_kitti = np.zeros((3, 4))  # Dummy values.
            r0_rect = Quaternion(axis=[1, 0, 0], angle=0)  # Dummy values.

            # Projection matrix.
            p_left_kitti = np.zeros((3, 4))
            p_left_kitti[:3, :3] = cs_record_cam[
                'camera_intrinsic']  # Cameras are always rectified.

            # Create KITTI style transforms.
            velo_to_cam_rot = velo_to_cam_kitti[:3, :3]
            velo_to_cam_trans = velo_to_cam_kitti[:3, 3]

            # Check that the rotation has the same format as in KITTI.
            assert (velo_to_cam_rot.round(0) == np.array([[0, -1,
                                                           0], [0, 0, -1],
                                                          [1, 0, 0]])).all()
            assert (velo_to_cam_trans[1:3] < 0).all()

            # Retrieve the token from the lidar.
            # Note that this may be confusing as the filename of the camera will include the timestamp of the lidar,
            # not the camera.
            filename_cam_full = sd_record_cam['filename']
            filename_lid_full = sd_record_lid['filename']
            # token = '%06d' % token_idx # Alternative to use KITTI names.
            token_idx += 1

            # Convert image (jpg to png).
            src_im_path = os.path.join(self.nusc.dataroot, filename_cam_full)
            dst_im_path = os.path.join(image_folder, sample_token + '.png')
            if not os.path.exists(dst_im_path):
                im = Image.open(src_im_path)
                im.save(dst_im_path, "PNG")

            # Convert lidar.
            # Note that we are only using a single sweep, instead of the commonly used n sweeps.
            src_lid_path = os.path.join(self.nusc.dataroot, filename_lid_full)
            dst_lid_path = os.path.join(lidar_folder, sample_token + '.bin')
            assert not dst_lid_path.endswith('.pcd.bin')
            pcl = LidarPointCloud.from_file(src_lid_path)
            pcl.rotate(
                kitti_to_nu_lidar_inv.rotation_matrix)  # In KITTI lidar frame.
            with open(dst_lid_path, "w") as lid_file:
                pcl.points.T.tofile(lid_file)

            # Add to tokens.
            tokens.append(sample_token)

            # Create calibration file.
            kitti_transforms = dict()
            kitti_transforms['P0'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms['P1'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms['P2'] = p_left_kitti  # Left camera transform.
            kitti_transforms['P3'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms[
                'R0_rect'] = r0_rect.rotation_matrix  # Cameras are already rectified.
            kitti_transforms['Tr_velo_to_cam'] = np.hstack(
                (velo_to_cam_rot, velo_to_cam_trans.reshape(3, 1)))
            kitti_transforms['Tr_imu_to_velo'] = imu_to_velo_kitti
            calib_path = os.path.join(calib_folder, sample_token + '.txt')
            with open(calib_path, "w") as calib_file:
                for (key, val) in kitti_transforms.items():
                    val = val.flatten()
                    val_str = '%.12e' % val[0]
                    for v in val[1:]:
                        val_str += ' %.12e' % v
                    calib_file.write('%s: %s\n' % (key, val_str))

            # Write label file.
            label_path = os.path.join(label_folder, sample_token + '.txt')
            if os.path.exists(label_path):
                print('Skipping existing file: %s' % label_path)
                continue
            else:
                print('Writing file: %s' % label_path)
            with open(label_path, "w") as label_file:
                for sample_annotation_token in sample_annotation_tokens:
                    sample_annotation = self.nusc.get('sample_annotation',
                                                      sample_annotation_token)

                    # Get box in LIDAR frame.
                    _, box_lidar_nusc, _ = self.nusc.get_sample_data(
                        lidar_token,
                        box_vis_level=BoxVisibility.NONE,
                        selected_anntokens=[sample_annotation_token])
                    box_lidar_nusc = box_lidar_nusc[0]

                    # Truncated: Set all objects to 0 which means untruncated.
                    truncated = 0.0

                    # Occluded: Set all objects to full visibility as this information is not available in nuScenes.
                    occluded = 0

                    # Convert nuScenes category to nuScenes detection challenge category.
                    detection_name = category_to_detection_name(
                        sample_annotation['category_name'])

                    # Skip categories that are not part of the nuScenes detection challenge.
                    if detection_name is None:
                        continue

                    # Convert from nuScenes to KITTI box format.
                    box_cam_kitti = KittiDB.box_nuscenes_to_kitti(
                        box_lidar_nusc, Quaternion(matrix=velo_to_cam_rot),
                        velo_to_cam_trans, r0_rect)

                    # Project 3d box to 2d box in image, ignore box if it does not fall inside.
                    bbox_2d = KittiDB.project_kitti_box_to_image(box_cam_kitti,
                                                                 p_left_kitti,
                                                                 imsize=imsize)
                    if bbox_2d is None:
                        continue

                    # Set dummy score so we can use this file as result.
                    box_cam_kitti.score = 0

                    # Convert box to output string format.
                    output = KittiDB.box_to_string(name=detection_name,
                                                   box=box_cam_kitti,
                                                   bbox_2d=bbox_2d,
                                                   truncation=truncated,
                                                   occlusion=occluded)

                    # Write to disk.
                    label_file.write(output + '\n')
Beispiel #5
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def parse_sample(sample_token, nusc):

    ret_dict = {}
    sample_data = nusc.get('sample', sample_token)
    timestamp = sample_data['timestamp']

    # First Step: Get lidar points in global frame cord!
    lidar_token = sample_data['data']['LIDAR_TOP']
    lidar_data = nusc.get('sample_data', lidar_token)
    pcl_path = osp.join(nusc.dataroot, lidar_data['filename'])
    pc = LidarPointCloud.from_file(pcl_path)

    # lidar point in point sensor frame

    cs_record = nusc.get('calibrated_sensor',
                         lidar_data['calibrated_sensor_token'])
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix)
    pc.translate(np.array(cs_record['translation']))

    # Second step: transform from ego to the global frame.
    poserecord = nusc.get('ego_pose', lidar_data['ego_pose_token'])
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix)
    pc.translate(np.array(poserecord['translation']))

    # First Step finished! pc in global frame

    for cam_name in CamNames:
        cam_token = sample_data['data'][cam_name]
        _, boxes, _ = nusc.get_sample_data(cam_token,
                                           box_vis_level=BoxVisibility.ANY)

        all_points = []
        all_sf = []
        for box in boxes:
            ann_token = box.token
            points, sf, _ = get_sf_ann(ann_token, timestamp,
                                       deepcopy(pc.points[:3, ]), nusc)
            if points is not None:
                all_points.append(points)
                all_sf.append(sf)

        if len(all_points) > 0:
            points = np.concatenate(all_points, axis=-1)
            sf = np.concatenate(all_sf, axis=-1)
        else:
            # set meta[''] = None!
            ret_dict[cam_name] = None
            continue
        # transform points to ego pose; change sf's orentiation

        # change from global to ego pose
        points = points - np.array(poserecord['translation'])[:, np.newaxis]
        points = np.dot(
            Quaternion(poserecord['rotation']).rotation_matrix.T, points)

        sf = np.dot(Quaternion(poserecord['rotation']).rotation_matrix.T, sf)

        # change from ego to camera
        cam_data = nusc.get('sample_data', cam_token)
        cam_cs = nusc.get('calibrated_sensor',
                          cam_data['calibrated_sensor_token'])

        # transform points for ego pose to camera pose
        cam_points = deepcopy(points) - np.array(
            cam_cs['translation'])[:, np.newaxis]
        cam_points = np.dot(
            Quaternion(cam_cs['rotation']).rotation_matrix.T, cam_points)
        cam_sf = np.dot(Quaternion(cam_cs['rotation']).rotation_matrix.T, sf)

        ret_points = np.concatenate([cam_points, cam_sf], axis=0)
        ret_dict[cam_name] = ret_points

    return ret_dict
Beispiel #6
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import matplotlib.pyplot as plt

nusc = NuScenes(version='v1.0-mini',
                dataroot='/media/aicore/Daten/aicore 2TB/nuScenes/v1.0-mini',
                verbose=True)

my_sample = nusc.get('sample', 'cd9964f8c3d34383b16e9c2997de1ed0')
#nusc.render_sample(my_sample['token'])

sample_record = nusc.get('sample', my_sample['token'])
#nusc.list_sample(my_sample['token'])
for sd_token in sample_record['data'].values():
    sd_record = nusc.get('sample_data', sd_token)
    if sd_record['sensor_modality'] == 'lidar':
        pcl_path = osp.join(nusc.dataroot, sd_record['filename'])
        pc = LidarPointCloud.from_file(pcl_path)
        view = np.eye(4)
        print(pc.points.shape)
        count = 0
        points_in_horizion = np.transpose(
            view_points(pc.points[:3, :], view, normalize=True))
        for point in points_in_horizion:
            if np.sum(np.square(point[0:1])) > 2500:
                count += 1

        print(count, len(points_in_horizion))
        count = 0
        points = np.transpose(pc.points[:3, :])
        for point in points:
            if point[2] > 10:
                print(point)
Beispiel #7
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        def accumulate_class(curr_class_name):
            # curr_ev = TrackingEvaluation(self.tracks_gt, self.tracks_pred, curr_class_name, self.cfg.dist_fcn_callable,\
            #                              self.cfg.dist_th_tp, self.cfg.min_recall,\
            #                              num_thresholds=TrackingMetricData.nelem,\
            #                              metric_worst=self.cfg.metric_worst,\
            #                              verbose=self.verbose,\
            #                              output_dir=self.output_dir,\
            #                              render_classes=self.render_classes)
            #curr_md = curr_ev.accumulate()
            """
            Compute metrics for all recall thresholds of the current class.
            :return: TrackingMetricData instance which holds the metrics for each threshold.
            """
            # Init.
            if self.verbose:
                print('Computing metrics for class %s...\n' % curr_class_name)
            accumulators = []
            thresh_metrics = []
            init_outscen()
            #md = TrackingMetricData()

            # Skip missing classes.
            gt_box_count = 0
            gt_track_ids = set()
            for scene_tracks_gt in self.tracks_gt.values():
                for frame_gt in scene_tracks_gt.values():
                    for box in frame_gt:
                        if box.tracking_name == curr_class_name:
                            gt_box_count += 1
                            gt_track_ids.add(box.tracking_id)
            if gt_box_count == 0:
                print("gtboxcount=0")
                # Do not add any metric. The average metrics will then be nan.
                #return md

            # Register mot metrics.
            #mh = create_motmetrics()

            # Get thresholds.
            # Note: The recall values are the hypothetical recall (10%, 20%, ..).
            # The actual recall may vary as there is no way to compute it without trying all thresholds.
            thresholds = np.array(
                [0.1])  #, recalls = self.compute_thresholds(gt_box_count)
            #md.confidence = thresholds
            #md.recall_hypo = recalls
            if self.verbose:
                print('Computed thresholds\n')

            for t, threshold in enumerate(thresholds):
                # If recall threshold is not achieved, we assign the worst possible value in AMOTA and AMOTP.
                if np.isnan(threshold):
                    continue

                # Do not compute the same threshold twice.
                # This becomes relevant when a user submits many boxes with the exact same score.
                if threshold in thresholds[:t]:
                    continue
                    """
                        Accumulate metrics for a particular recall threshold of the current class.
                        The scores are only computed if threshold is set to None. This is used to infer the recall thresholds.
                        :param threshold: score threshold used to determine positives and negatives.
                        :return: (The MOTAccumulator that stores all the hits/misses/etc, Scores for each TP).
                    """
                accs = []
                scores = [
                ]  # The scores of the TPs. These are used to determine the recall thresholds initially.

                # Go through all frames and associate ground truth and tracker results.
                # Groundtruth and tracker contain lists for every single frame containing lists detections.
                tracks_gt = self.tracks_gt
                scene_num_id = 0
                sum_fp = 0
                sum_fn = 0
                for scene_id in tqdm.tqdm(list(tracks_gt.keys()),
                                          disable=not self.verbose,
                                          leave=False):  #按场景

                    # Initialize accumulator and frame_id for this scene
                    acc = MOTAccumulatorCustom()
                    frame_id = 0  # Frame ids must be unique across all scenes

                    # Retrieve GT and preds.
                    scene_tracks_gt = tracks_gt[scene_id]
                    scene_tracks_pred = self.tracks_pred[scene_id]
                    # if len(tracks_gt) == 151:
                    #     tracks_gt.pop('0')
                    # Visualize the boxes in this frame.
                    if curr_class_name in self.render_classes and threshold is not None and scene_num_id < scene_id_thr:

                        save_path = os.path.join(self.output_dir, 'render',
                                                 str(scene_id),
                                                 curr_class_name)
                        os.makedirs(save_path, exist_ok=True)
                        renderer = TrackingRenderer(save_path)
                    else:
                        renderer = None

                    for timestamp in scene_tracks_gt.keys():  #每个场景分别每帧
                        # Select only the current class.
                        frame_gt = scene_tracks_gt[timestamp]
                        frame_pred = scene_tracks_pred[timestamp]
                        frame_gt = [
                            f for f in frame_gt
                            if f.tracking_name == curr_class_name
                        ]
                        frame_pred = [
                            f for f in frame_pred
                            if f.tracking_name == curr_class_name
                        ]

                        # Threshold boxes by score. Note that the scores were previously averaged over the whole track.
                        if threshold is not None:
                            frame_pred = [
                                f for f in frame_pred
                                if f.tracking_score >= threshold
                            ]

                        # Abort if there are neither GT nor pred boxes.
                        gt_ids = [gg.tracking_id for gg in frame_gt]
                        pred_ids = [tt.tracking_id for tt in frame_pred]
                        if len(gt_ids) == 0 and len(pred_ids) == 0:
                            continue

                        # Calculate distances.
                        # Note that the distance function is hard-coded to achieve significant speedups via vectorization.
                        assert self.cfg.dist_fcn_callable.__name__ == 'center_distance'
                        if len(frame_gt) == 0 or len(frame_pred) == 0:
                            distances = np.ones((0, 0))
                        else:
                            gt_boxes = np.array(
                                [b.translation[:2] for b in frame_gt])
                            pred_boxes = np.array(
                                [b.translation[:2] for b in frame_pred])
                            distances = sklearn.metrics.pairwise.euclidean_distances(
                                gt_boxes, pred_boxes)

                        # Distances that are larger than the threshold won't be associated.
                        assert len(distances) == 0 or not np.all(
                            np.isnan(distances))
                        distances[distances >= self.cfg.dist_th_tp] = np.nan

                        # Accumulate results.
                        # Note that we cannot use timestamp as frameid as motmetrics assumes it's an integer.
                        acc.update(gt_ids,
                                   pred_ids,
                                   distances,
                                   frameid=frame_id)

                        # Store scores of matches, which are used to determine recall thresholds.
                        if threshold is not None:
                            events = acc.events.loc[frame_id]
                            matches = events[events.Type == 'MATCH']
                            match_ids = matches.HId.values
                            match_scores = [
                                tt.tracking_score for tt in frame_pred
                                if tt.tracking_id in match_ids
                            ]
                            scores.extend(match_scores)
                        else:
                            events = None

                        # Render the boxes in this frame.
                        if curr_class_name in self.render_classes and threshold is not None and scene_num_id < scene_id_thr:
                            # load lidar points  data按每帧加载
                            #https://github.com/nutonomy/nuscenes-devkit/blob/master/python-sdk/nuscenes/scripts/export_kitti.py
                            try:
                                frame0 = frame_pred[0]
                            except:
                                frame0 = scene_tracks_gt[timestamp][0]
                            sample = self.nusc.get(
                                'sample',
                                frame0.sample_token)  #frame_pred是该帧所有的物体
                            #sample_annotation_tokens = sample['anns'] #标注
                            #cam_front_token = sample['data'][cam_name]#某点位的图像
                            lidar_token = sample['data'][lidar_name]
                            # Retrieve sensor records.
                            #sd_record_cam = self.nusc.get('sample_data', cam_front_token)
                            sd_record_lid = self.nusc.get(
                                'sample_data', lidar_token)
                            cs_record = self.nusc.get(
                                'calibrated_sensor',
                                sd_record_lid["calibrated_sensor_token"])
                            pose_record = self.nusc.get(
                                'ego_pose', sd_record_lid["ego_pose_token"])
                            #cs_record_cam = self.nusc.get('calibrated_sensor', sd_record_cam['calibrated_sensor_token'])
                            #cs_record_lid = self.nusc.get('calibrated_sensor', sd_record_lid['calibrated_sensor_token'])
                            # Retrieve the token from the lidar.
                            # Note that this may be confusing as the filename of the camera will include the timestamp of the lidar,
                            # not the camera.
                            #filename_cam_full = sd_record_cam['filename']
                            filename_lid_full = sd_record_lid['filename']
                            src_lid_path = os.path.join(
                                datset_path, filename_lid_full)
                            points = LidarPointCloud.from_file(src_lid_path)

                            if scene_id == "4efbf4c0b77f467385fc2e19da45c989":  #or lidar_token == "16be583c31a2403caa6c158bb55ae616":#选择特定帧 上面要设成150个场景
                                renderer.render(events,
                                                timestamp,
                                                frame_gt,
                                                frame_pred,
                                                points,
                                                pose_record,
                                                cs_record,
                                                ifplotgt,
                                                threshold,
                                                ifpltsco,
                                                outscen_class,
                                                nusc=self.nusc,
                                                ifplthis=ifplthis)

                        # Increment the frame_id, unless there are no boxes (equivalent to what motmetrics does).
                        frame_id += 1

                    scene_num_id += 1

                    accs.append(acc)
                print("visually have done!")
                if outscen_class and renderer is not None:
                    print('trk_ratio:',TrackingRenderer.trk_ratio,'\n', 'fp_disrange:',TrackingRenderer.fp_disrange, '\n', 'fp_verange:', TrackingRenderer.fp_verange, '\n', 'fp_ptsnumrange:',TrackingRenderer.fp_ptsnumrange, '\n', \
                       'fpscorrange', TrackingRenderer.fpscorrange, '\n', 'gt_ratio', TrackingRenderer.gt_ratio, '\n', 'vis_ratio', TrackingRenderer.vis_ratio, '\n', 'fn_disrange', TrackingRenderer.fn_disrange, '\n',\
                        'fn_verange', TrackingRenderer.fn_verange, '\n', 'fn_ptsnumrange', TrackingRenderer.fn_ptsnumrange, '\n', 'ids_verange', TrackingRenderer.ids_verange, '\n', 'ids_factratio', TrackingRenderer.ids_factratio, '\n',\
                        'gt_ptsnumrange', TrackingRenderer.gt_ptsnumrange, 'at least fault_datas', TrackingRenderer.fault_datas  )
    def process_token_to_kitti(self, sample_token: str) -> None:
        # Get sample data.
        sample = self.nusc.get('sample', sample_token)
        sample_annotation_tokens = sample['anns']

        lidar_token = sample['data'][self.lidar_name]
        sd_record_lid = self.nusc.get('sample_data', lidar_token)
        cs_record_lid = self.nusc.get('calibrated_sensor',
                                      sd_record_lid['calibrated_sensor_token'])
        for cam_name in self.cams_to_see:
            cam_front_token = sample['data'][cam_name]
            token_to_write = cam_front_token

            # Retrieve sensor records.
            sd_record_cam = self.nusc.get('sample_data', cam_front_token)
            cs_record_cam = self.nusc.get(
                'calibrated_sensor', sd_record_cam['calibrated_sensor_token'])
            cam_height = sd_record_cam['height']
            cam_width = sd_record_cam['width']
            imsize = (cam_width, cam_height)

            # Combine transformations and convert to KITTI format.
            # Note: cam uses same conventions in KITTI and nuScenes.
            lid_to_ego = transform_matrix(cs_record_lid['translation'],
                                          Quaternion(
                                              cs_record_lid['rotation']),
                                          inverse=False)
            ego_to_cam = transform_matrix(cs_record_cam['translation'],
                                          Quaternion(
                                              cs_record_cam['rotation']),
                                          inverse=True)
            velo_to_cam = np.dot(ego_to_cam, lid_to_ego)

            # Convert from KITTI to nuScenes LIDAR coordinates, where we apply velo_to_cam.
            velo_to_cam_kitti = np.dot(
                velo_to_cam, self.kitti_to_nu_lidar.transformation_matrix)

            # Currently not used.
            imu_to_velo_kitti = np.zeros((3, 4))  # Dummy values.
            r0_rect = Quaternion(axis=[1, 0, 0], angle=0)  # Dummy values.

            # Projection matrix.
            p_left_kitti = np.zeros((3, 4))
            # Cameras are always rectified.
            p_left_kitti[:3, :3] = cs_record_cam['camera_intrinsic']

            # Create KITTI style transforms.
            velo_to_cam_rot = velo_to_cam_kitti[:3, :3]
            velo_to_cam_trans = velo_to_cam_kitti[:3, 3]

            # Check that the rotation has the same format as in KITTI.
            assert (velo_to_cam_trans[1:3] < 0).all()

            # Retrieve the token from the lidar.
            # Note that this may be confusing as the filename of the camera will
            # include the timestamp of the lidar,
            # not the camera.
            filename_cam_full = sd_record_cam['filename']
            filename_lid_full = sd_record_lid['filename']

            # Convert image (jpg to png).
            src_im_path = os.path.join(self.nusc.dataroot, filename_cam_full)
            dst_im_path = os.path.join(self.image_folder,
                                       token_to_write + '.png')
            if not os.path.exists(dst_im_path):
                im = Image.open(src_im_path)
                im.save(dst_im_path, "PNG")

            # Convert lidar.
            # Note that we are only using a single sweep, instead of the commonly used n sweeps.
            src_lid_path = os.path.join(self.nusc.dataroot, filename_lid_full)
            dst_lid_path = os.path.join(self.lidar_folder,
                                        token_to_write + '.bin')

            pcl = LidarPointCloud.from_file(src_lid_path)
            # In KITTI lidar frame.
            pcl.rotate(self.kitti_to_nu_lidar_inv.rotation_matrix)
            with open(dst_lid_path, "w") as lid_file:
                pcl.points.T.tofile(lid_file)

            # Add to tokens.
            # tokens.append(token_to_write)

            # Create calibration file.
            kitti_transforms = dict()
            kitti_transforms['P0'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms['P1'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms['P2'] = p_left_kitti  # Left camera transform.
            kitti_transforms['P3'] = np.zeros((3, 4))  # Dummy values.
            # Cameras are already rectified.
            kitti_transforms['R0_rect'] = r0_rect.rotation_matrix
            kitti_transforms['Tr_velo_to_cam'] = np.hstack(
                (velo_to_cam_rot, velo_to_cam_trans.reshape(3, 1)))
            kitti_transforms['Tr_imu_to_velo'] = imu_to_velo_kitti
            calib_path = os.path.join(self.calib_folder,
                                      token_to_write + '.txt')
            with open(calib_path, "w") as calib_file:
                for (key, val) in kitti_transforms.items():
                    val = val.flatten()
                    val_str = '%.12e' % val[0]
                    for v in val[1:]:
                        val_str += ' %.12e' % v
                    calib_file.write('%s: %s\n' % (key, val_str))

            # Write label file.
            label_path = os.path.join(self.label_folder,
                                      token_to_write + '.txt')
            if os.path.exists(label_path):
                print('Skipping existing file: %s' % label_path)
                continue
            # else:
            #     print('Writing file: %s' % label_path)
            with open(label_path, "w") as label_file:
                for sample_annotation_token in sample_annotation_tokens:
                    sample_annotation = self.nusc.get('sample_annotation',
                                                      sample_annotation_token)

                    # Get box in LIDAR frame.
                    _, box_lidar_nusc, _ = self.nusc.get_sample_data(
                        lidar_token,
                        box_vis_level=BoxVisibility.NONE,
                        selected_anntokens=[sample_annotation_token])
                    box_lidar_nusc = box_lidar_nusc[0]

                    # Truncated: Set all objects to 0 which means untruncated.
                    truncated = 0.0

                    # Occluded: Set all objects to full visibility as this information is
                    # not available in nuScenes.
                    occluded = 0

                    detection_name = sample_annotation['category_name']
                    # category_to_detection_name(sample_annotation['category_name'])
                    # Skip categories that are not part of the nuScenes detection challenge. - disabled
                    if detection_name is None:
                        continue

                    # Convert from nuScenes to KITTI box format.
                    box_cam_kitti = KittiDB.box_nuscenes_to_kitti(
                        box_lidar_nusc, Quaternion(matrix=velo_to_cam_rot),
                        velo_to_cam_trans, r0_rect)

                    # Project 3d box to 2d box in image, ignore box if it does not fall inside.
                    bbox_2d = KittiDB.project_kitti_box_to_image(box_cam_kitti,
                                                                 p_left_kitti,
                                                                 imsize=imsize)
                    if bbox_2d is None and not self.get_all_detections:
                        continue
                    elif bbox_2d is None and self.get_all_detections:
                        bbox_2d = (-1.0, -1.0, -1.0, -1.0
                                   )  # default KITTI bbox

                    # Set dummy score so we can use this file as result.
                    box_cam_kitti.score = 0

                    # Convert box to output string format.
                    output = KittiDB.box_to_string(name=detection_name,
                                                   box=box_cam_kitti,
                                                   bbox_2d=bbox_2d,
                                                   truncation=truncated,
                                                   occlusion=occluded)

                    # Write to disk.
                    label_file.write(output + '\n')
Beispiel #9
0
def load_point_cloud(nuscenes, sample_data):

    # Load point cloud
    lidar_path = os.path.join(nuscenes.dataroot, sample_data['filename'])
    pcl = LidarPointCloud.from_file(lidar_path)
    return pcl.points[:3, :].T
Beispiel #10
0
def get_pointcloud(nusc,
                   bottom_left,
                   top_right,
                   box,
                   pointsensor_token: str,
                   camera_token: str,
                   min_dist: float = 1.0) -> Tuple:
    """
	Given a point sensor (lidar/radar) token and camera sample_data token, load point-cloud and map it to the image
	plane.
	:param pointsensor_token: Lidar/radar sample_data token.
	:param camera_token: Camera sample_data token.
	:param min_dist: Distance from the camera below which points are discarded.
	:return (pointcloud <np.float: 2, n)>, coloring <np.float: n>, image <Image>).
	"""
    sample_data = nusc.get("sample_data", camera_token)
    explorer = NuScenesExplorer(nusc)

    cam = nusc.get('sample_data', camera_token)
    pointsensor = nusc.get('sample_data', pointsensor_token)

    im = Image.open(osp.join(nusc.dataroot, cam['filename']))

    sample_rec = explorer.nusc.get('sample', pointsensor['sample_token'])
    chan = pointsensor['channel']
    ref_chan = 'LIDAR_TOP'
    # pc, times = LidarPointCloud.from_file_multisweep(nusc, sample_rec, chan, ref_chan, nsweeps = 10)
    file_name = os.path.join(
        nusc.dataroot,
        nusc.get('sample_data', sample_rec['data'][chan])['filename'])
    pc = LidarPointCloud.from_file(file_name)
    data_path, boxes, camera_intrinsic = nusc.get_sample_data(
        pointsensor_token, selected_anntokens=[box.token])
    pcl_box = boxes[0]

    original_points = pc.points.copy()

    # Points live in the point sensor frame. So they need to be transformed via global to the image plane.
    # First step: transform the point-cloud to the ego vehicle frame for the timestamp of the sweep.
    cs_record = nusc.get('calibrated_sensor',
                         pointsensor['calibrated_sensor_token'])
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix)
    pc.translate(np.array(cs_record['translation']))

    # Second step: transform to the global frame.
    poserecord = nusc.get('ego_pose', pointsensor['ego_pose_token'])
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix)
    pc.translate(np.array(poserecord['translation']))

    # Third step: transform into the ego vehicle frame for the timestamp of the image.
    poserecord = nusc.get('ego_pose', cam['ego_pose_token'])
    pc.translate(-np.array(poserecord['translation']))
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix.T)

    # Fourth step: transform into the camera.
    cs_record = nusc.get('calibrated_sensor', cam['calibrated_sensor_token'])
    pc.translate(-np.array(cs_record['translation']))
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix.T)

    # Fifth step: actually take a "picture" of the point cloud.
    depths = pc.points[2, :]

    # Take the actual picture (matrix multiplication with camera-matrix + renormalization).
    points = view_points(pc.points[:3, :],
                         np.array(cs_record['camera_intrinsic']),
                         normalize=True)
    center = np.array([[box.center[0]], [box.center[1]], [box.center[2]]])
    box_center = view_points(center,
                             np.array(cs_record['camera_intrinsic']),
                             normalize=True)
    box_corners = box.corners()

    image_center = np.asarray([((bottom_left[0] + top_right[0]) / 2),
                               ((bottom_left[1] + top_right[1]) / 2), 1])

    # rotate to make the ray passing through the image_center into the z axis
    z_axis = np.linalg.lstsq(np.array(cs_record['camera_intrinsic']),
                             image_center,
                             rcond=None)[0]
    v = np.asarray([z_axis[0], z_axis[1], z_axis[2]])
    z = np.asarray([0., 0., 1.])
    normal = np.cross(v, z)
    theta = np.arccos(np.dot(v, z) / np.sqrt(v.dot(v)))
    new_pts = []
    new_corner = []
    old_pts = []
    points_3 = points_3[:3, :]
    translate = np.dot(rotation_matrix(normal, theta), image_center)
    for point in points_3.T:
        new_pts = new_pts + [np.dot(rotation_matrix(normal, theta), point)]
    for corner in box_corners.T:
        new_corner = new_corner + [
            np.dot(rotation_matrix(normal, theta), corner)
        ]

    points = np.asarray(new_pts)
    original_points = original_points[:3, :].T
    new_corners = np.asarray(new_corner)

    reverse_matrix = rotation_matrix(normal, -theta)

    # Sample 400 points
    if np.shape(new_pts)[0] > 400:
        mask = np.random.choice(points.shape[0], 400, replace=False)
        points = points[mask, :]
        original_points = original_points[mask, :]

    shift = np.expand_dims(np.mean(points, axis=0), 0)
    points = points - shift  # center
    new_corners = new_corners - shift  # center
    dist = np.max(np.sqrt(np.sum(points**2, axis=1)), 0)
    points = points / dist  # scale
    new_corners = new_corners / dist  # scale

    # Compute offset from point to corner
    n = np.shape(points)[0]
    offset = np.zeros((n, 8, 3))
    for i in range(0, n):
        for j in range(0, 8):
            offset[i][j] = new_corners[j] - points[i]

    # Compute mask on which points lie inside of the box
    m = []
    for point in original_points:
        if in_box(point, pcl_box.corners()) == True:
            m = m + [1]
        else:
            m = m + [0]
    m = np.asarray(m)

    return points.T, m, offset, reverse_matrix, new_corners
Beispiel #11
0
def map_pointcloud_to_image(nusc,
                            pointsensor_token: str,
                            camera_token: str,
                            min_dist: float = 1.0,
                            render_intensity: bool = False,
                            show_lidarseg: bool = False):
    """
    Given a point sensor (lidar/radar) token and camera sample_data token, load pointcloud and map it to the image
    plane.
    :param pointsensor_token: Lidar/radar sample_data token.
    :param camera_token: Camera sample_data token.
    :param min_dist: Distance from the camera below which points are discarded.
    :param render_intensity: Whether to render lidar intensity instead of point depth.
    :param show_lidarseg: Whether to render lidar intensity instead of point depth.
    :param filter_lidarseg_labels: Only show lidar points which belong to the given list of classes. If None
        or the list is empty, all classes will be displayed.
    :param lidarseg_preds_bin_path: A path to the .bin file which contains the user's lidar segmentation
                                    predictions for the sample.
    :return (pointcloud <np.float: 2, n)>, coloring <np.float: n>, image <Image>).
    """

    cam = nusc.get('sample_data', camera_token)
    pointsensor = nusc.get('sample_data', pointsensor_token)
    pcl_path = osp.join(nusc.dataroot, pointsensor['filename'])
    if pointsensor['sensor_modality'] == 'lidar':
        # Ensure that lidar pointcloud is from a keyframe.
        assert pointsensor['is_key_frame'], \
            'Error: Only pointclouds which are keyframes have lidar segmentation labels. Rendering aborted.'
        pc = LidarPointCloud.from_file(pcl_path)
    else:
        pc = RadarPointCloud.from_file(pcl_path)
    im = Image.open(osp.join(nusc.dataroot, cam['filename']))

    # Points live in the point sensor frame. So they need to be transformed via global to the image plane.
    # First step: transform the pointcloud to the ego vehicle frame for the timestamp of the sweep.
    cs_record = nusc.get('calibrated_sensor',
                         pointsensor['calibrated_sensor_token'])
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix)
    pc.translate(np.array(cs_record['translation']))

    # Second step: transform from ego to the global frame.
    poserecord = nusc.get('ego_pose', pointsensor['ego_pose_token'])
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix)
    pc.translate(np.array(poserecord['translation']))

    # Third step: transform from global into the ego vehicle frame for the timestamp of the image.
    poserecord = nusc.get('ego_pose', cam['ego_pose_token'])
    pc.translate(-np.array(poserecord['translation']))
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix.T)

    # Fourth step: transform from ego into the camera.
    cs_record = nusc.get('calibrated_sensor', cam['calibrated_sensor_token'])
    pc.translate(-np.array(cs_record['translation']))
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix.T)

    # Fifth step: actually take a "picture" of the point cloud.
    # Grab the depths (camera frame z axis points away from the camera).
    depths = pc.points[2, :]

    if render_intensity:
        assert pointsensor['sensor_modality'] == 'lidar', 'Error: Can only render intensity for lidar, ' \
                                                          'not %s!' % pointsensor['sensor_modality']
        # Retrieve the color from the intensities.
        # Performs arbitary scaling to achieve more visually pleasing results.
        intensities = pc.points[3, :]
        intensities = (intensities - np.min(intensities)) / (
            np.max(intensities) - np.min(intensities))
        intensities = intensities**0.1
        intensities = np.maximum(0, intensities - 0.5)
        coloring = intensities

    else:
        # Retrieve the color from the depth.
        coloring = depths

    # Take the actual picture (matrix multiplication with camera-matrix + renormalization).
    points = view_points(pc.points[:3, :],
                         np.array(cs_record['camera_intrinsic']),
                         normalize=True)

    # Remove points that are either outside or behind the camera. Leave a margin of 1 pixel for aesthetic reasons.
    # Also make sure points are at least 1m in front of the camera to avoid seeing the lidar points on the camera
    # casing for non-keyframes which are slightly out of sync.
    mask = np.ones(depths.shape[0], dtype=bool)
    mask = np.logical_and(mask, depths > min_dist)
    mask = np.logical_and(mask, points[0, :] > 1)
    mask = np.logical_and(mask, points[0, :] < im.size[0] - 1)
    mask = np.logical_and(mask, points[1, :] > 1)
    mask = np.logical_and(mask, points[1, :] < im.size[1] - 1)
    points = points[:, mask]
    coloring = coloring[mask]

    return points, coloring, im
def validate_submission(nusc: NuScenes,
                        results_folder: str,
                        eval_set: str,
                        verbose: bool = False) -> None:
    """
    Checks if a results folder is valid. The following checks are performed:
    - Check that the submission folder is according to that described in
      https://github.com/nutonomy/nuscenes-devkit/blob/master/python-sdk/nuscenes/eval/lidarseg/README.md
    - Check that the submission.json is of the following structure:
        {"meta": {"use_camera": false,
                  "use_lidar": true,
                  "use_radar": false,
                  "use_map": false,
                  "use_external": false}}
    - Check that each each lidar sample data in the evaluation set is present and valid.

    :param nusc: A NuScenes object.
    :param results_folder: Path to the folder.
    :param eval_set: The dataset split to evaluate on, e.g. train, val or test.
    :param verbose: Whether to print messages during the evaluation.
    """
    mapper = LidarsegClassMapper(nusc)
    num_classes = len(mapper.coarse_name_2_coarse_idx_mapping)

    if verbose:
        print('Checking if folder structure of {} is correct...'.format(
            results_folder))

    # Check that {results_folder}/{eval_set} exists.
    results_meta_folder = os.path.join(results_folder, eval_set)
    assert os.path.exists(results_meta_folder), \
        'Error: The folder containing the submission.json ({}) does not exist.'.format(results_meta_folder)

    # Check that {results_folder}/{eval_set}/submission.json exists.
    submisson_json_path = os.path.join(results_meta_folder, 'submission.json')
    assert os.path.exists(submisson_json_path), \
        'Error: submission.json ({}) does not exist.'.format(submisson_json_path)

    # Check that {results_folder}/lidarseg/{eval_set} exists.
    results_bin_folder = os.path.join(results_folder, 'lidarseg', eval_set)
    assert os.path.exists(results_bin_folder), \
        'Error: The folder containing the .bin files ({}) does not exist.'.format(results_bin_folder)

    if verbose:
        print('\tPassed.')

    if verbose:
        print('Checking contents of {}...'.format(submisson_json_path))

    with open(submisson_json_path) as f:
        submission_meta = json.load(f)
        valid_meta = {
            "use_camera", "use_lidar", "use_radar", "use_map", "use_external"
        }
        assert valid_meta == set(submission_meta['meta'].keys()), \
            '{} must contain {}.'.format(submisson_json_path, valid_meta)
        for meta_key in valid_meta:
            meta_key_type = type(submission_meta['meta'][meta_key])
            assert meta_key_type == bool, 'Error: Value for {} should be bool, not {}.'.format(
                meta_key, meta_key_type)

    if verbose:
        print('\tPassed.')

    if verbose:
        print(
            'Checking if all .bin files for {} exist and are valid...'.format(
                eval_set))
    sample_tokens = get_samples_in_eval_set(nusc, eval_set)
    for sample_token in tqdm(sample_tokens, disable=not verbose):
        sample = nusc.get('sample', sample_token)

        # Get the sample data token of the point cloud.
        sd_token = sample['data']['LIDAR_TOP']

        # Load the predictions for the point cloud.
        lidarseg_pred_filename = os.path.join(results_bin_folder,
                                              sd_token + '_lidarseg.bin')
        assert os.path.exists(lidarseg_pred_filename), \
            'Error: The prediction .bin file {} does not exist.'.format(lidarseg_pred_filename)
        lidarseg_pred = np.fromfile(lidarseg_pred_filename, dtype=np.uint8)

        # Check number of predictions for the point cloud.
        if len(
                nusc.lidarseg
        ) > 0:  # If ground truth exists, compare the no. of predictions with that of ground truth.
            lidarseg_label_filename = os.path.join(
                nusc.dataroot,
                nusc.get('lidarseg', sd_token)['filename'])
            assert os.path.exists(lidarseg_label_filename), \
                'Error: The ground truth .bin file {} does not exist.'.format(lidarseg_label_filename)
            lidarseg_label = np.fromfile(lidarseg_label_filename,
                                         dtype=np.uint8)
            num_points = len(lidarseg_label)
        else:  # If no ground truth is available, compare the no. of predictions with that of points in a point cloud.
            pointsensor = nusc.get('sample_data', sd_token)
            pcl_path = os.path.join(nusc.dataroot, pointsensor['filename'])
            pc = LidarPointCloud.from_file(pcl_path)
            points = pc.points
            num_points = points.shape[1]

        assert num_points == len(lidarseg_pred), \
            'Error: There are {} predictions for lidar sample data token {} ' \
            'but there are only {} points in the point cloud.'\
            .format(len(lidarseg_pred), sd_token, num_points)

        assert all((lidarseg_pred > 0) & (lidarseg_pred < num_classes)), \
            "Error: Array for predictions in {} must be between 1 and {} (inclusive)."\
            .format(lidarseg_pred_filename, num_classes - 1)

    if verbose:
        print('\tPassed.')

    if verbose:
        print(
            'Results folder {} successfully validated!'.format(results_folder))
Beispiel #13
0
    def nuscenes_gt_to_kitti(self) -> None:
        """
        Converts nuScenes GT annotations to KITTI format.
        """
        kitti_to_nu_lidar = Quaternion(axis=(0, 0, 1), angle=np.pi / 2)
        kitti_to_nu_lidar_inv = kitti_to_nu_lidar.inverse
        imsize = (1600, 900)

        token_idx = 0  # Start tokens from 0.

        # Get assignment of scenes to splits.
        split_logs = create_splits_logs(self.split, self.nusc)

        scene_splits = create_splits_scenes(verbose=False)
        scene_to_log = {
            scene['name']: self.nusc.get('log', scene['log_token'])['logfile']
            for scene in self.nusc.scene
        }
        logs = set()
        scenes = scene_splits[self.split]
        for scene in scenes:
            logs.add(scene_to_log[scene])
        # print(len(scenes), len(logs))

        split_mapping = {"train": "training", "val": "testing"}

        # Create output folders.
        label_folder = os.path.join(self.nusc_kitti_dir,
                                    split_mapping[self.split], 'label_2')
        calib_folder = os.path.join(self.nusc_kitti_dir,
                                    split_mapping[self.split], 'calib')
        image_folder = os.path.join(self.nusc_kitti_dir,
                                    split_mapping[self.split], 'image_2')
        lidar_folder = os.path.join(self.nusc_kitti_dir,
                                    split_mapping[self.split], 'velodyne')
        for folder in [label_folder, calib_folder, image_folder, lidar_folder]:
            if not os.path.isdir(folder):
                os.makedirs(folder)

        # Use only the samples from the current split.
        sample_tokens = self._split_to_samples(split_logs)
        # sample_tokens = sample_tokens[:self.image_count]

        # print(len(sample_tokens))
        tokens = []
        if self.split == "train":
            split_file = [
                os.path.join(self.nusc_kitti_dir, "train.txt"),
                os.path.join(self.nusc_kitti_dir, "val.txt")
            ]
        elif self.split == 'val':
            split_file = os.path.join(self.nusc_kitti_dir, "test.txt")
        # if os.path.isfile(split_file):
        #     os.remove(split_file)
        if self.split == "train":
            cnt = 0
            with open(split_file[0], "w") as f:
                for seq in list(self.sequence_mapping.keys())[:-150]:
                    for tk in self.sequence_mapping[seq]:
                        f.write("%06d" % tk + "\n")
                        cnt += 1
            # print(cnt)

            cnt = 0
            with open(split_file[1], "w") as f:
                for seq in list(self.sequence_mapping.keys())[-150:]:
                    for tk in self.sequence_mapping[seq]:
                        f.write("%06d" % tk + "\n")
                        cnt += 1
            # print(cnt)
        elif self.split == "val":
            with open(split_file, "w") as f:
                for seq in self.sequence_mapping.keys():
                    for tk in self.sequence_mapping[seq]:
                        f.write("%06d" % tk + "\n")

        for idx, sample_token in enumerate(sample_tokens):

            # Get sample data.
            sample = self.nusc.get('sample', sample_token)
            sample_annotation_tokens = sample['anns']
            cam_front_token = sample['data'][self.cam_name]
            lidar_token = sample['data'][self.lidar_name]
            sample_name = "%06d" % idx

            # Retrieve sensor records.
            sd_record_cam = self.nusc.get('sample_data', cam_front_token)
            sd_record_lid = self.nusc.get('sample_data', lidar_token)
            cs_record_cam = self.nusc.get(
                'calibrated_sensor', sd_record_cam['calibrated_sensor_token'])
            cs_record_lid = self.nusc.get(
                'calibrated_sensor', sd_record_lid['calibrated_sensor_token'])

            # Combine transformations and convert to KITTI format.
            # Note: cam uses same conventions in KITTI and nuScenes.
            lid_to_ego = transform_matrix(cs_record_lid['translation'],
                                          Quaternion(
                                              cs_record_lid['rotation']),
                                          inverse=False)
            ego_to_cam = transform_matrix(cs_record_cam['translation'],
                                          Quaternion(
                                              cs_record_cam['rotation']),
                                          inverse=True)
            velo_to_cam = np.dot(ego_to_cam, lid_to_ego)

            # Convert from KITTI to nuScenes LIDAR coordinates, where we apply velo_to_cam.
            velo_to_cam_kitti = np.dot(velo_to_cam,
                                       kitti_to_nu_lidar.transformation_matrix)

            # Currently not used.
            imu_to_velo_kitti = np.zeros((3, 4))  # Dummy values.
            r0_rect = Quaternion(axis=[1, 0, 0], angle=0)  # Dummy values.

            # Projection matrix.
            p_left_kitti = np.zeros((3, 4))
            p_left_kitti[:3, :3] = cs_record_cam[
                'camera_intrinsic']  # Cameras are always rectified.

            # Create KITTI style transforms.
            velo_to_cam_rot = velo_to_cam_kitti[:3, :3]
            velo_to_cam_trans = velo_to_cam_kitti[:3, 3]

            # Check that the rotation has the same format as in KITTI.
            assert (velo_to_cam_rot.round(0) == np.array([[0, -1,
                                                           0], [0, 0, -1],
                                                          [1, 0, 0]])).all()
            assert (velo_to_cam_trans[1:3] < 0).all()

            # Retrieve the token from the lidar.
            # Note that this may be confusing as the filename of the camera will include the timestamp of the lidar,
            # not the camera.
            filename_cam_full = sd_record_cam['filename']
            filename_lid_full = sd_record_lid['filename']
            # token = '%06d' % token_idx # Alternative to use KITTI names.
            token_idx += 1

            # Convert image (jpg to png).
            src_im_path = os.path.join(self.nusc.dataroot, filename_cam_full)
            dst_im_path = os.path.join(image_folder, sample_name + '.png')
            if not os.path.exists(dst_im_path):
                im = Image.open(src_im_path)
                im.save(dst_im_path, "PNG")

            # Convert lidar.
            # Note that we are only using a single sweep, instead of the commonly used n sweeps.
            src_lid_path = os.path.join(self.nusc.dataroot, filename_lid_full)
            dst_lid_path = os.path.join(lidar_folder, sample_name + '.bin')
            assert not dst_lid_path.endswith('.pcd.bin')
            pcl = LidarPointCloud.from_file(src_lid_path)
            # pcl, _ = LidarPointCloud.from_file_multisweep_future(self.nusc, sample, self.lidar_name, self.lidar_name, nsweeps=5)
            pcl.rotate(
                kitti_to_nu_lidar_inv.rotation_matrix)  # In KITTI lidar frame.
            with open(dst_lid_path, "w") as lid_file:
                pcl.points.T.tofile(lid_file)

            # Add to tokens.
            tokens.append(sample_token)

            # Create calibration file.
            kitti_transforms = dict()
            kitti_transforms['P0'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms['P1'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms['P2'] = p_left_kitti  # Left camera transform.
            kitti_transforms['P3'] = np.zeros((3, 4))  # Dummy values.
            kitti_transforms[
                'R0_rect'] = r0_rect.rotation_matrix  # Cameras are already rectified.
            kitti_transforms['Tr_velo_to_cam'] = np.hstack(
                (velo_to_cam_rot, velo_to_cam_trans.reshape(3, 1)))
            kitti_transforms['Tr_imu_to_velo'] = imu_to_velo_kitti
            calib_path = os.path.join(calib_folder, sample_name + '.txt')
            with open(calib_path, "w") as calib_file:
                for (key, val) in kitti_transforms.items():
                    val = val.flatten()
                    val_str = '%.12e' % val[0]
                    for v in val[1:]:
                        val_str += ' %.12e' % v
                    calib_file.write('%s: %s\n' % (key, val_str))

            # Write label file.
            label_path = os.path.join(label_folder, sample_name + '.txt')
            if os.path.exists(label_path):
                # print('Skipping existing file: %s' % label_path)
                continue
            # else:
            #     print('Writing file: %s' % label_path)

            objects = []
            for sample_annotation_token in sample_annotation_tokens:
                sample_annotation = self.nusc.get('sample_annotation',
                                                  sample_annotation_token)

                # Get box in LIDAR frame.
                _, box_lidar_nusc, _ = self.nusc.get_sample_data(
                    lidar_token,
                    box_vis_level=BoxVisibility.NONE,
                    selected_anntokens=[sample_annotation_token])
                box_lidar_nusc = box_lidar_nusc[0]

                # Truncated: Set all objects to 0 which means untruncated.
                truncated = 0.0

                # Occluded: Set all objects to full visibility as this information is not available in nuScenes.
                occluded = 0

                obj = dict()

                # Convert nuScenes category to nuScenes detection challenge category.
                obj["detection_name"] = category_to_detection_name(
                    sample_annotation['category_name'])

                # Skip categories that are not part of the nuScenes detection challenge.
                if obj["detection_name"] is None or obj[
                        "detection_name"] not in CLASS_MAP.keys():
                    continue

                obj["detection_name"] = CLASS_MAP[obj["detection_name"]]

                # Convert from nuScenes to KITTI box format.
                obj["box_cam_kitti"] = KittiDB.box_nuscenes_to_kitti(
                    box_lidar_nusc, Quaternion(matrix=velo_to_cam_rot),
                    velo_to_cam_trans, r0_rect)

                # Project 3d box to 2d box in image, ignore box if it does not fall inside.
                bbox_2d = project_to_2d(obj["box_cam_kitti"], p_left_kitti,
                                        imsize[1], imsize[0])
                if bbox_2d is None:
                    continue
                obj["bbox_2d"] = bbox_2d["bbox"]
                obj["truncated"] = bbox_2d["truncated"]

                # Set dummy score so we can use this file as result.
                obj["box_cam_kitti"].score = 0

                v = np.dot(obj["box_cam_kitti"].rotation_matrix,
                           np.array([1, 0, 0]))
                rot_y = -np.arctan2(v[2], v[0])
                obj["alpha"] = -np.arctan2(
                    obj["box_cam_kitti"].center[0],
                    obj["box_cam_kitti"].center[2]) + rot_y
                obj["depth"] = np.linalg.norm(
                    np.array(obj["box_cam_kitti"].center[:3]))
                objects.append(obj)

            objects = postprocessing(objects, imsize[1], imsize[0])

            with open(label_path, "w") as label_file:
                for obj in objects:
                    # Convert box to output string format.
                    output = box_to_string(name=obj["detection_name"],
                                           box=obj["box_cam_kitti"],
                                           bbox_2d=obj["bbox_2d"],
                                           truncation=obj["truncated"],
                                           occlusion=obj["occluded"],
                                           alpha=obj["alpha"])
                    label_file.write(output + '\n')
Beispiel #14
0
def map_pointcloud_to_image_(nusc: NuScenes,
                             bbox,
                             pointsensor_token: str,
                             camera_token: str,
                             min_dist: float = 1.0,
                             dist_thresh: float = 0.1,
                             visualize: bool = False) -> Tuple:
    """
    Given a point sensor (lidar/radar) token and camera sample_data token, load point-cloud and map it to the image
    plane.
    :param nusc: NuScenes instance.
    :param bbox: object coordinates in the current image.
    :param pointsensor_token: Lidar/radar sample_data token.
    :param camera_token: Camera sample_data token.
    :param min_dist: Distance from the camera below which points are discarded.
    :param dist_thresh: Threshold to consider points within floor plane.
    :return (points_ann <np.float: 2, n)>, coloring_ann <np.float: n>, ori_points_ann<np.float: 3, n)>, image <Image>).
    """
    cam = nusc.get('sample_data', camera_token)  # Sample camera info
    pointsensor = nusc.get('sample_data',
                           pointsensor_token)  # Sample point cloud
    # pcl_path is the path from root to the pointCloud file
    pcl_path = osp.join(nusc.dataroot, pointsensor['filename'])
    # Open the pointCloud path using the Lidar or Radar class
    if pointsensor['sensor_modality'] == 'lidar':
        # Read point cloud with LidarPointCloud (4 x samples) --> X, Y, Z and intensity
        pc = LidarPointCloud.from_file(pcl_path)
        # To access the points pc.points
    else:
        # Read point cloud with LidarPointCloud (18 x samples) -->
        # https://github.com/nutonomy/nuscenes-devkit/blob/master/python-sdk/nuscenes/utils/data_classes.py#L296
        pc = RadarPointCloud.from_file(pcl_path)

    # Open image of the interest camera
    im = Image.open(osp.join(nusc.dataroot, cam['filename']))

    # Save original points (X, Y and Z) coordinates in LiDAR frame
    ori_points = pc.points[:3, :].copy()

    # Points live in the point sensor frame. So they need to be transformed via global to the image plane.
    # First step: transform the point-cloud to the ego vehicle frame for the timestamp of the sweep.
    cs_record = nusc.get('calibrated_sensor',
                         pointsensor['calibrated_sensor_token']
                         )  # Transformation matrix of pointCloud
    # Transform the Quaternion into a rotation matrix and use method rotate in PointCloud class to rotate
    # Map from the laser sensor to ego_pose
    # The method is a dot product between cs_record['rotation'] (3 x 3) and points (3 x points)
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix)
    # Add the traslation vector between ego vehicle and sensor
    # The method translate is an addition cs_record['translation'] (3,) and points (3 x points)
    pc.translate(np.array(cs_record['translation']))

    # Second step: transform to the global frame.
    poserecord = nusc.get('ego_pose', pointsensor['ego_pose_token'])
    # Same step as before, map from ego_pose to world coordinate frame
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix)
    pc.translate(np.array(poserecord['translation']))

    # Third step: transform into the ego vehicle frame for the timestamp of the image.
    poserecord = nusc.get('ego_pose', cam['ego_pose_token'])
    # Same step as before, map from world coordinate frame to ego vehicle frame for the timestamp of the image.
    pc.translate(-np.array(poserecord['translation']))
    pc.rotate(Quaternion(poserecord['rotation']).rotation_matrix.T)

    # Fourth step: transform into the camera.
    cs_record = nusc.get('calibrated_sensor', cam['calibrated_sensor_token'])
    # Same step as before, map from ego at camera timestamp to camera
    pc.translate(-np.array(cs_record['translation']))
    pc.rotate(Quaternion(cs_record['rotation']).rotation_matrix.T)

    # Fifth step: actually take a "picture" of the point cloud.
    # Grab the depths (camera frame z axis points away from the camera).
    depths = pc.points[2, :]

    # Retrieve the color from the depth.
    coloring = depths

    # Take the actual picture (matrix multiplication with camera-matrix + renormalization).
    # Normalization means to divide the X and Y coordinates by the depth
    # The output dim (3 x n_points) where the 3rd row are ones.
    points = view_points(pc.points[:3, :],
                         np.array(cs_record['camera_intrinsic']),
                         normalize=True)

    # bounding box coordinates
    min_x, min_y, max_x, max_y = [int(points_b) for points_b in bbox]

    # Floor segmentation
    points_img, coloring_img, ori_points_img = segment_floor(
        points, coloring, ori_points, (im.size[0], im.size[1]), dist_thresh,
        1.0)

    # Filter the points within the annotaiton
    # Create a mask of bools the same size of depth points
    mask_ann = np.ones(coloring_img.shape[0], dtype=bool)
    # Keep points such as X coordinate is bigger than bounding box minimum coordinate
    mask_ann = np.logical_and(mask_ann, points_img[0, :] > min_x + 1)
    # remove points such as X coordinate is bigger than bounding box maximum coordinate
    mask_ann = np.logical_and(mask_ann, points_img[0, :] < max_x - 1)
    # Keep points such as Y coordinate is bigger than bounding box minimum coordinate
    mask_ann = np.logical_and(mask_ann, points_img[1, :] > min_y + 1)
    # remove points such as Y coordinate is bigger than bounding box maximum coordinate
    mask_ann = np.logical_and(mask_ann, points_img[1, :] < max_y - 1)
    # Keep only the interest points
    points_ann = points_img[:, mask_ann]
    coloring_ann = coloring_img[mask_ann]
    ori_points_ann = ori_points_img[:, mask_ann]

    if visualize:
        plt.figure(figsize=(9, 16))
        plt.imshow(im)
        plt.scatter(points_ann[0, :], points_ann[1, :], c=coloring_ann, s=5)
        plt.axis('off')

    return points_ann, coloring_ann, ori_points_ann, im
Beispiel #15
0
def get_lidar_data(nusc, sample_rec, nsweeps, min_distance):
    """Similar to LidarPointCloud.from_file_multisweep but returns in the ego car frame."""
    # Init.
    points = np.zeros((5, 0))

    # Get reference pose and timestamp.
    ref_sd_token = sample_rec['data']['LIDAR_TOP']
    ref_sd_rec = nusc.get('sample_data', ref_sd_token)
    ref_pose_rec = nusc.get('ego_pose', ref_sd_rec['ego_pose_token'])
    ref_cs_rec = nusc.get('calibrated_sensor',
                          ref_sd_rec['calibrated_sensor_token'])
    ref_time = 1e-6 * ref_sd_rec['timestamp']

    # Homogeneous transformation matrix from global to _current_ ego car frame.
    car_from_global = transform_matrix(ref_pose_rec['translation'],
                                       Quaternion(ref_pose_rec['rotation']),
                                       inverse=True)

    # Aggregate current and previous sweeps.
    sample_data_token = sample_rec['data']['LIDAR_TOP']
    current_sd_rec = nusc.get('sample_data', sample_data_token)
    for _ in range(nsweeps):
        # Load up the pointcloud and remove points close to the sensor.
        current_pc = LidarPointCloud.from_file(
            os.path.join(nusc.dataroot, current_sd_rec['filename']))
        current_pc.remove_close(min_distance)

        # Get past pose.
        current_pose_rec = nusc.get('ego_pose',
                                    current_sd_rec['ego_pose_token'])
        global_from_car = transform_matrix(current_pose_rec['translation'],
                                           Quaternion(
                                               current_pose_rec['rotation']),
                                           inverse=False)

        # Homogeneous transformation matrix from sensor coordinate frame to ego car frame.
        current_cs_rec = nusc.get('calibrated_sensor',
                                  current_sd_rec['calibrated_sensor_token'])
        car_from_current = transform_matrix(current_cs_rec['translation'],
                                            Quaternion(
                                                current_cs_rec['rotation']),
                                            inverse=False)

        # Fuse four transformation matrices into one and perform transform.
        trans_matrix = reduce(
            np.dot, [car_from_global, global_from_car, car_from_current])
        current_pc.transform(trans_matrix)

        # Add time vector which can be used as a temporal feature.
        time_lag = 1e-6 * current_sd_rec['timestamp'] - ref_time
        times = np.full((1, current_pc.nbr_points()), time_lag)

        new_points = np.concatenate((current_pc.points, times), 0)
        points = np.concatenate((points, new_points), 1)

        # Abort if there are no previous sweeps.
        if current_sd_rec['prev'] == '':
            break
        else:
            current_sd_rec = nusc.get('sample_data', current_sd_rec['prev'])

    return points
Beispiel #16
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def get_lidar_data(nusc, sample_rec, nsweeps, min_distance):
    """
    Returns at most nsweeps of lidar in the ego frame.
    Returned tensor is 5(x, y, z, reflectance, dt) x N
    Adapted from https://github.com/nutonomy/nuscenes-devkit/blob/master/python-sdk/nuscenes/utils/data_classes.py#L56
    """
    points = np.zeros((5, 0))

    # Get reference pose and timestamp.
    ref_sd_token = sample_rec['data']['LIDAR_TOP']
    ref_sd_rec = nusc.get('sample_data', ref_sd_token)
    ref_pose_rec = nusc.get('ego_pose', ref_sd_rec['ego_pose_token'])
    ref_cs_rec = nusc.get('calibrated_sensor',
                          ref_sd_rec['calibrated_sensor_token'])
    ref_time = 1e-6 * ref_sd_rec['timestamp']

    # Homogeneous transformation matrix from global to _current_ ego car frame.
    car_from_global = transform_matrix(ref_pose_rec['translation'],
                                       Quaternion(ref_pose_rec['rotation']),
                                       inverse=True)

    # Aggregate current and previous sweeps.
    sample_data_token = sample_rec['data']['LIDAR_TOP']
    current_sd_rec = nusc.get('sample_data', sample_data_token)
    for _ in range(nsweeps):
        # Load up the pointcloud and remove points close to the sensor.
        current_pc = LidarPointCloud.from_file(
            os.path.join(nusc.dataroot, current_sd_rec['filename']))
        current_pc.remove_close(min_distance)

        # Get past pose.
        current_pose_rec = nusc.get('ego_pose',
                                    current_sd_rec['ego_pose_token'])
        global_from_car = transform_matrix(current_pose_rec['translation'],
                                           Quaternion(
                                               current_pose_rec['rotation']),
                                           inverse=False)

        # Homogeneous transformation matrix from sensor coordinate frame to ego car frame.
        current_cs_rec = nusc.get('calibrated_sensor',
                                  current_sd_rec['calibrated_sensor_token'])
        car_from_current = transform_matrix(current_cs_rec['translation'],
                                            Quaternion(
                                                current_cs_rec['rotation']),
                                            inverse=False)

        # Fuse four transformation matrices into one and perform transform.
        trans_matrix = reduce(
            np.dot, [car_from_global, global_from_car, car_from_current])
        current_pc.transform(trans_matrix)

        # Add time vector which can be used as a temporal feature.
        time_lag = ref_time - 1e-6 * current_sd_rec['timestamp']
        times = time_lag * np.ones((1, current_pc.nbr_points()))

        new_points = np.concatenate((current_pc.points, times), 0)
        points = np.concatenate((points, new_points), 1)

        # Abort if there are no previous sweeps.
        if current_sd_rec['prev'] == '':
            break
        else:
            current_sd_rec = nusc.get('sample_data', current_sd_rec['prev'])

    return points